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Passive Solar
and Energy Efficient Home Design
EVERY HOME IS A SOLAR HOME
It is a fact, that everything we build is solar. When we ignore
solar energy during the design stages we end up
with a building which may benefit from solar, though it is just
as likely to be beat up by solar energy.
A passive solar design will not only lower your utility bills,
it will be comfortable. Comfort is priceless.
The following guidelines are drawn from research and practical
application, from successes and failures,
from the experience of our ancestors who lived in caves, and
from recent computer generated studies.
Orientation: The longest wall of the home should face
south. The winter sun rises South of East and sets
South of West. Placing more glass on the South wall will ensure
that your home receives free solar energy.
This same orientation helps to prevent the high summer sun from
entering the home.
A compass will point to magnetic North/South, but a solar
home or collector works best when it faces TRUE SOUTH.
In the El Paso area true south is 12 degrees East of magnetic
South. This declination from magnetic south varies across the
country depending on longitude.
Solar Access: Buildings or trees too close to your
home could block the low winter sun.
Windows: The amount of glass on the South wall may
equal 7% of the homes total square footage.
(Example: 2,000 Sq. Ft. = 140 Sq. Ft. of glass.)
To avoid overheating, this amount of glass should not be exceeded.
The 7% applies to conventional home construction with standard
floorm coverings such as carpet, vinyl tile, or wood. Increasing
glass area above 7% will require additional thermal mass, i.e.
concrete/tile floors, rock, brick, concrete or adobe walls.
The 7% amount is NET sq. ft. or the total window area less
the trim etc.
Multiply the entire window by .8 to get the net glass area.
Example: A 3'0"X5'0"window is 15 sq. ft.
15 X .8 = 12 sq. ft. net
East and North glass should be limited to no more than 4%
of total sq. ft. (Maximum)
West glass should not exceed 2% of total sq.ft.(MAXIMUM)
Landscaping: Plant deciduous or evergreen trees on the east,
west and north sides of the home. Xeriscape!
Avoid dark colors, inside and out.
Insulation:
Insulate exterior of slab/foundation with extruded polystyrene
sheets. R-5 for moderate climates, R-10 for colder climates.
Sole Plate: Install sill sealer under the bottom plate
of all exterior walls, on both the first and second floors.
Walls: In moderate climates use 2X4 frame walls with
R-13 batts and R-4 rigid insulated sheathing boards (1"
expanded polystyrene). For Cold climates, use 2X6 frame walls
with R-19 batts and the same R-4 sheathing.
Sprayed cellulose insulation should be considered because, though
more expensive than batts, is more effective because it fills
voids and reduces air leakage."
Attic: Ceiling Install R-30 insulation, blown
in type is preferable, for moderate climates. Levels of R-38
to R-50 are recommended for colder climates
IMPORTANT: Prior to installing wall insulation, use
cans of expanding foam insulation and/or caulk to seal all electrical
and plumbing penetrations, around doors and windows.
Tape/seal all joints in ductwork.
Duct work should be installed in interior (heated) space so that
heat or cold is not lost to unheated spaces (attic).
Furrdowns should be sheathed and sealed prior to installing duct.
Insulate walls surrounding furnace closets and seal return
air plenum.
Doors: Install steel or fiberglass
insulated exterior doors that have an insulation value of R-5.9
or greater. Lower R-value doors can be used in conjunction with
a storm door.
Ventilation: Place and size windows to take advantage
of natural ventilation and prevailing breezes.
Fans: The use of ceiling fans can drastically reduce the
running time of air conditioners.
Contact your local county agent or state energy office for
recommendations specific to your area.
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